Sympathetic Nerve Blocks

Sympathetic Nerve Blocks

Sympathetic blockade can be accomplished by a variety of techniques, including intrathecal, epi-dural, and paravertebral blocks. Unfortunately, these approaches usually block both somatic and sympathetic fibers. Problems with differential spinal and epidural techniques are discussed below. The following techniques specifically block sympathetic fibers and can be used to define the role of the sym-pathetic system in a patient’s pain and possibly also provide long-term pain relief. The most common indications for sympathetic nerve blocks include reflex sympathetic dystrophy, visceral pain, acute herpetic neuralgia, postherpetic pain, and periph-eral vascular disease. Isolated sympathetic blockade to a region is characterized by loss of sympathetic tone, as evidenced by increased cutaneous blood flow and cutaneous temperature, and by unaltered somatic sensation. Other tests include loss of the skin conductance (sympathogalvanic reflex) and sweat response (ninhydrin, cobalt blue, or starch tests) following a painful stimulus.